How it works...

The following code demonstrates the new addition:

public static void main(String... arg) {
  int horsePower = 246;
  int payload = Truck.convertKgToPounds(1500);
  int vehicleWeight = Truck.convertKgToPounds(1800);
  Truck truck = 
      FactoryVehicle.buildTruck(payload, vehicleWeight, horsePower);
  System.out.println("Weight in pounds: " + vehicleWeight);
  int kg = truck.getWeightKg(vehicleWeight);
  System.out.println("Weight converted to kg: " + kg);
  System.out.println("Weight converted back to pounds: " + 
                                       Truck.convertKgToPounds(kg));
}

The results of the test do not change: